Field of the Invention
Embodiments of the present invention relate generally to a method for generating writing data, and more specifically, to a method for generating writing data to be input to the writing apparatus, for example.
Description of Related Art
In recent years, with high integration of LSI, the circuit line width (critical dimension) required for semiconductor devices is becoming progressively narrower. As a method for forming an exposure mask (also called a reticle) used to form circuit patterns on these semiconductor devices, the electron beam (EB) writing technique having excellent resolution is employed.
As an example employing the electron beam writing technique, the writing apparatus using multi-beams can be cited. Compared with the case of writing a pattern with a single electron beam, since in multi-beam writing it is possible to irradiate multiple beams at a time, the throughput can be greatly increased. For example, in a writing apparatus employing a multi-beam system, multi-beams are formed by letting portions of an electron beam emitted from an electron gun pass through a corresponding hole of a plurality of holes formed in the mask, blanking control is performed for each beam, and each unblocked beam is reduced by an optical system and deflected by a deflector so as to irradiate a desired position on a target object or “sample”.
In the multi-beam writing apparatus, pattern data (writing data) converted from CAD data is input. Then, data conversion processing is performed on the input pattern data so as to advance to writing processing. In this process, it goes without saying that the amount of pattern data to be input to the writing apparatus is preferably small. Therefore, the pattern data defining a plurality of figure patterns is defined by data-compressed format (e.g., refer to Japanese Patent Application Laid-open (JP-A) No. 2005-079115).
In the writing apparatus, conventionally, correction processing of pattern size CD is performed with respect to dimensional variations resulting from a proximity effect that occurs by backscattering whose influence range is about 10 μm, a fogging effect whose influence range is on the order of mm, and a chromium loading effect whose influence range is on the order of mm. If needed to correct dimensional variation resulting from a phenomenon whose influence range is smaller than about 10 μm, it may be possible to define the amount of dose modulation for the figure pattern itself in the writing data to be input to the writing apparatus, for example. However, for correcting a small influence range such as described above, in the case of employing the above-described method, since the size of the figure pattern itself is too large, it is necessary to divide the figure pattern into a plurality of small figure patterns, and to define a dose modulation amount for each small figure pattern. Accordingly, there is a problem that the amount of the writing data will be excessively large.